In manufacturing an aluminum heat exchanger, there are a number of brazing portions and flux is applied to those brazing portions.
As a method of supplying flux to a surface of an aluminum member, a method of applying flux suspended in water has been conventionally employed. However, in supplying the flux by this method, it is required to provide a step for vaporizing the water content before the brazing, and the flux suspension hardly adheres to uneven portions and curved portions and therefore it was difficult to supply a given amount of flux to those portions.
To solve the aforementioned problems, a technology for improving the flux adhesive property by using flux composition containing flux and binder that resolves and volatilizes at the time of brazing (Patent Document 1) and a technology for causing flux adherence by static electricity (Patent Document 2) have been proposed.    Patent Document 1: Japanese Unexamined Laid-opened Patent Application Publication No. H09-29487    Patent Document 2: Japanese Patent No. 3603710